Date: Wed, 22 Jul 2009 22:26:44 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Jung-uk Kim <jkim@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r195820 - in head/sys/amd64: amd64 include Message-ID: <20090722192644.GX55190@deviant.kiev.zoral.com.ua> In-Reply-To: <200907221445.25404.jkim@FreeBSD.org> References: <200907221432.n6MEWcXB043644@svn.freebsd.org> <200907221445.25404.jkim@FreeBSD.org>
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--JX3/dhvb8vz6C4q6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 22, 2009 at 02:44:52PM -0400, Jung-uk Kim wrote: > On Wednesday 22 July 2009 10:32 am, Konstantin Belousov wrote: > > Author: kib > > Date: Wed Jul 22 14:32:38 2009 > > New Revision: 195820 > > URL: http://svn.freebsd.org/changeset/base/195820 > > > > Log: > > When the page caching attributes are changed, after new mapping > > is established, OS shall flush the caches on all processors that > > may have used the mapping previously. This operation is not needed > > if processors support self-snooping. If not, but clflush > > instruction is implemented on the CPU, series of the clflush can be > > used on the mapping region. Otherwise, we have to flush the whole > > cache. The later operation is very expensive, and AMD-made CPUs do > > not have self-snooping. > > > > Implement cache flush for remapped region by using clflush for > > amd64, when supported by CPU. >=20 > --- >8 --- SKIP --- >8 --- >=20 > > @@ -267,6 +274,13 @@ outw(u_int port, u_short data) > > } > > > > static __inline void > > +mfence(void) > > +{ > > + > > + __asm__ __volatile("mfence" : : : "memory"); > > +} > > + > > +static __inline void > > ia32_pause(void) > > { > > __asm __volatile("pause"); >=20 > Is there any reason why you want mfence() instead of mb() from=20 > machine/atomic.h? Char-to-char equal implementation of pmap_invalidate_cache_range() is developed for i386. Note that mb() is a barrier, while Intel notes that clflush only ordered with mfence. On i386, mb() is locked nop. --JX3/dhvb8vz6C4q6 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAkpnZ/MACgkQC3+MBN1Mb4hYgQCeMEq2b2hRipR/ZiUch0rZyozj 4J0AoLuTY2BE8OgChbfKRu3BlDy2Ju7H =IylY -----END PGP SIGNATURE----- --JX3/dhvb8vz6C4q6--
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